package main

import (
	"bufio"
	"fmt"
	"os"
)

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Scan()
	line := sc.Text()

	fs := make([]int32, 128)

	for _, s := range line {
		if fs[s] == 0 {
			fmt.Printf("%c", s)
			fs[s] = 1
		}
	}
}
